Ruthenium (Ru), a silvery-white transition metal with the atomic number 44, is a member of the platinum group metals. An element’s chemical behavior is dictated by its outermost electrons, known as valence electrons. For Ruthenium, the total number of valence electrons available for chemical bonding is eight.
Understanding the Concept of Valence Electrons
Valence electrons are the electrons located in the outermost electron shell of an atom. These are the electrons an atom uses to form chemical bonds with other atoms. Their number and arrangement determine how an element will interact and react chemically. Elements with similar numbers of valence electrons often exhibit comparable chemical properties, which is the foundational principle behind the organization of the periodic table.
These outer electrons are the ones most loosely held by the atomic nucleus. They are the first to be involved in the transfer or sharing of electrons during a chemical reaction, seeking to achieve a stable, full outer shell.
Determining Ruthenium’s Valence Electrons
Ruthenium is classified as a transition metal, meaning its valence count includes electrons from both its outermost \(s\) subshell and its inner, but incomplete, \(d\) subshell. Transition metals do not follow the simple valence rules applied to main-group elements. Ruthenium is located in Group 8 and Period 5 of the periodic table.
The electron configuration of a neutral Ruthenium atom is \([\text{Kr}] 4d^7 5s^1\). The valence electrons are counted from the \(5s\) orbital (one electron) and the partially filled \(4d\) orbital (seven electrons). This totals eight valence electrons, reflecting the sum of the \(s\) and \(d\) electrons and Ruthenium’s placement in Group 8.
Chemical Behavior and Oxidation States
The presence of eight valence electrons gives Ruthenium a high degree of chemical flexibility, leading to a wide array of possible oxidation states. Ruthenium compounds can exhibit oxidation states ranging from \(-2\) up to \(+8\). The most common and stable oxidation states observed in Ruthenium chemistry are \(+2\), \(+3\), and \(+4\).
The ability to lose a varying number of its eight valence electrons means Ruthenium can participate in diverse chemical reactions. The maximum oxidation state of \(+8\) is achieved in the compound Ruthenium tetroxide (\(\text{RuO}_4\)), a highly volatile and strong oxidizing agent. This versatility makes Ruthenium an effective and widely used catalyst in industrial processes.
Practical Applications of Ruthenium
Ruthenium is known for being hard, brittle, and highly resistant to corrosion. Adding small amounts of Ruthenium to platinum or palladium creates alloys with increased strength and durability. These strengthened alloys are used to create wear-resistant electrical contacts in high-performance electronics.
Ruthenium is also utilized in thick-film resistors and in the manufacturing of advanced semiconductors through chemical vapor deposition processes. Furthermore, the element is employed in advanced energy technologies, including as a catalyst in certain types of fuel cells and in dye-sensitized solar cells to enhance light absorption efficiency.